The 27-year-old utility had been one of the NRL's premier players without a deal beyond 2025 before the 11th-placed Tigers confirmed a two-year extension on Friday afternoon.
Coach Benji Marshall, usually reticent to address recruitment publicly, had been open about his desire to keep Doueihi amid interest from St George Illawarra in recent weeks.
The signing is a big boost for the Tigers' rebuild, with Doueihi's handy minutes at halfback helping the club transition into life with young Latu Fainu as starting No.7.
Doueihi most recently starred as starting halfback in the 28-14 defeat of finals-bound Canterbury on Sunday, one of the best wins in Marshall's two seasons as coach.
"I'm excited about what's building here, it's a great group who are pulling in the same direction. I'm looking forward to seeing what we can achieve over the next two years," Doueihi said.
Doueihi's form and deal come after a horror run of three anterior cruciate ligament injuries clouded his future in the game.
But he has since rebounded for a Tigers side that appears to be turning the corner following three consecutive last-placed finishes.
"His injuries have been well documented and to see first-hand the way he approached his rehab, his return and the way he's playing now is so pleasing for everyone at the club," Marshall said.
"The characteristics Adam showed right throughout that period are the cornerstone for the form we see him in this season and what make him such an important part of our group."
Doueihi made his NRL debut with South Sydney in 2018 and played in the 2019 preliminary final loss before joining the Tigers the following season.
The Lebanon international's versatility has become his calling card across 113 first-grade games, having started in every back-line position as well as lock.